I found this tutorial on how to create an impact crater... http://www.world-machine.com/tutorials/craters/craters.htmlAnd I downloaded the sample project. The weird thing is that the Curves is causing the entire terrain to become 2D. It's eliminating the height entirely and I'm not sure how to fix it. I'm using WM Professional.

I didn't change anything, I simply opened the file and it doesn't work. Any idea how to fix this?

A simple fix is to plug the terrain into a displacement node, just plug it into both inputs and don't mess around with the device itself, stay sure it stays on 0.

The way World Machine works is kinda weird sometimes, but the output of a displacement will always be a 3D terrain, if you want your 2D heightmap back just combine it with 0 power with another 2D mask, like a height selector